How to measure intradiscal pressure of an intervertebral disc model in Abaqus 2

[Emre SENGUL]

Hi,

I have a vertebra FE model in Abaqus. I can probe the related stresses but I don't know how to measure total pressure in nucleus of an intervertebral disc. Is there any way for this?(For example, I can obtain total facet forces from history outputs)

Best regards

 

[IceBreakerSours]

You could remove a few elements from the disc where the nucleus is supposed to be and use the fluid cavity feature to be able to report out the pressure. Read and play with examples in the documentation.

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[FEA way]

It will be easier if you separate the nucleus from the rest of intervertebral disc using partitions (if you haven't done it already). Then create element set for nucleus. You can use PRESS output variable (equivalent pressure stress = hydrostatic stress).

 

[Emre SENGUL]

Thanks for your suggestions. I tired fluid cavity model before but standard meshing method is proper and easier for my FE model. The nucleus part is already separated from intervertebral disc. So, I will try to use PRESS output variable.

 

[IceBreakerSours]

I suggested fluid cavity because you get to do more with it when it comes to modeling disc degeneration. For instance, you could model fluid leakage, which may result in relatively higher zygapophyseal joint interaction forces or higher shear forces in the annulus fibrosus under certain loading conditions.

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[Emre SENGUL]

oh, I understand now. I can also try fluid cavity method for my further studies. Thanks.

 

[Emre SENGUL]

Hi guys,

I used PRESS output variable for my current study. It gave pressures of all nodes in nucleus part. Then, I calculated mean value of them by using 'operate on XY data' feature. Thus, I took logical results.

Thank you

Note: I will try fluid cavity method for my further studies.

 

[IceBreakerSours]

FYI

There is not a lot of data on intradiscal pressure (IDP) from (live) human subjects except for Alf Nachemson, Hans-Joachim Wilke, and one other person whose name escapes me. From a computational standpoint, comparisons with IDP should be taken only as a sanity check. Adams and Dolan, Neil D. Broom, Jill PG Urban's experimental results are more appealing to me if I were to model disc degeneration - in gory detail.

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